When is it appropriate to use a hyphen? [duplicate]

Solution 1:

There's no single answer to this: various conventions exist depending on personal preference and/or the in-house (or "in house", or "inhouse") style guide for the particular publication you're writing for. That said, I think that in general, using hyphens between the elements of compound nouns is less common nowadays (so people would tend to write "side dish", "ticket office" etc, not "side-dish", "ticket-office"). I also get the impression (with no hard statistics to back it up) that US usage favours the hyphen still a bit more than UK usage.

I think a common modern convention is to use hyphens mainly for cases of ambiguity or where a compound functions as an adjective (or perhaps more specifically, compounds "in attributive position"[*]). The hyphen is maybe a bit more common with compound verbs as well.

[*] Bauer, L. (2006), "Compounds and Minor Word-formation Types" in The Handbook of English Linguistics, Blackwell, pp. 483-506.

From the same author:

We might, for instance, find coffee pot, coffee-pot or coffeepot, depending on the dictionary we care to consult. When even dictionaries fail to agree, we can be sure that actual usage provides a bewlidering amount of variation. (p. 485)

Solution 2:

You may want to consult The Economist's style guide entry on the subject, it provides useful guidelines. In particular:

In general, try to avoid putting hyphens into words formed of one word and a short prefix ... but long words thus formed and unfamiliar combinations, especially if they would involve running several consonants together, may benefit from a hyphen

Adverbs are also focused upon:

Adverbs do not need to be linked to participles or adjectives by hyphens in simple constructions ... but if the adverb is one of two words together being used adjectivally, a hyphen may be needed ... the hyphen is especially likely to be needed if the adverb is short and common, such as ill, little, much and well. Less-common adverbs, including all those that end -ly, are less likely to need hyphens

The specific cases you are asking about were not addressed.